Transmission especially for motor vehicles

ABSTRACT

A transmission, especially for motor vehicles, which includes an infinitely variable converter adjoining an engine shaft and several pairs of meshing gears following the converter which are adapted to be selectively engaged or disengaged by way of shifting clutches, whereby one shifting clutch is adapted to connect the engine shaft with a pair of meshing gears, while actually selectively engaged, and the converter, such as a hydrostatic converter, is adapted to be internally uncoupled.

llmted States Patent 1191 1111 3,782,225 Grabow Jan. 1, 11974 [54]TRANSMISSION ESPECIALLY FOR MOTOR 3.095.757 7/1963 Thoma 74/687 VEHICLES3,204,486 9/1965 DeLalio 74/687 3,286,541 11/1966 Dearnley et a1. 74/687X lnvenmri Frltz Grabow, g, Germany 3,580,107 5/1971 Orshansky, Jr.74/687 [73] Assigneez DaimlebBenz Akfiengeseuschafi 3,593,596 7/1971Race et a1 74/720 t t, G S agar ermdny Primary Examiner-Charles J. Myhre[22] Filed: Apr- 1971 Assistant Examiner-Thomas C. Perry Appl. No.:130,612

[30] Foreign Application Priority Data Apr. 3, 1970 Germany P 20 15945.9

[52] US. Cl. 74/720, 74/733 [51] Fl6h 47/02 [58] Field of Search 74/720,733, 687

[56] References Cited UNITED STATES PATENTS 2,618,988 11/1952 Woydt74/733 2,891,419 6/1959 Bzidalini 74/720 X 2,962,915 12/1960 Wiggermann74/733 X AttorneyC raig, Antonelli & Hill 5 7 ABSTRACT A transmission,especially for motor vehicles, which includes an infinitely variableconverter adjoining an engine shaft and several pairs of meshing gearsfollowing the converter which are adapted to be selectively engaged ordisengaged by way of shifting clutches, whereby one shifting clutch isadapted to connect the engine shaft with a pair of meshing gears, whileactually selectively engaged, and the converter, such as a hydrostaticconverter, is adapted to be internally uncoupled.

18 Claims, 1 Drawing Figure TRANSMISSION ESPECIALLY FOR MOTOR VEHICLESThe present invention relates to a transmission, especially for motorvehicles, which includes an infinitely variable torque converteradjoining the engine shaft and gear pairs following the converter, whichare adapted to be selectively engaged or disengaged by way of shiftingclutches.

Transmissions of this type are normally intended for heavy vehicles andtrain engines and should allow variable converting speed reductions from1:1 to 1:16. However, this is not possible with the known convertersalone because, for example, a hydrostatic converter which consists of apump and of a motor, permits only a maximum conversion of about 1:4unless an excessively large hydrostatic motor or also several motors areused.

In order to enable nonetheless a larger converting range, Le, a largerange of changes in transmission ratios, it is known to equip such atransmission with a hydrostatic converter which is adapted to beselectively connected in its output with several transmission ratios orspeed reduction steps consisting of pairs of gear wheels. With thisknown type of construction the torque conversion range is passed throughseveral times, for which purpose the converting ranges are selected bymechanical shifting means accompanied with an interruption in tractionforce.

The present invention is concerned with the task to provide atransmission of the aforementioned type which has high variable speedreductions that can be passed through without interruption in tractiveforce. The present invention essentially consists in that a shiftingclutch is provided, by means of which the engine shaft is adapted to becoupled with the engaged transmission ratio or gear wheel step inby-passing relationship to the converter, and in that the converterincludes a mechanism for the internal disengagement or uncouplingthereof. The possibility is created thereby that the converter, after ithas once passed through or traversed its entire converter rangespeed-reduced by one gear step or transmission ratio, can once moretraverse or pass through its entire converter range in another gear stepor transmission ratio without the occurrence of an interruption intractive force because during the shifting of the converter and of thegear pair, the engine shaft can be coupled directly with thetransmission output shaft while simultaneously an internal uncoupling ofthe converter is undertaken, in which condition the converter can bereturned to its original position without the transmission of torque bythe converter during such shifting operation.

An advantageous construction of the present invention is obtained if ahydrostatic converter is provided whose circulatory system is adapted tobe short- .circuited within the area of its pump. Such a hydrostaticconverter permits in a simple manner an internal uncoupling during whichits converting range can be shifted without the transmission of torqueby the converter during such shifting operation.

A simple embodiment of this invention, in which the converter passesthrough its converting range twice, is obtained if the infinitelyvariable converter is connected with the engine shaftby way of a pair of'gears, wherebyjthe output of the converter is adjoined by twoselectively engageable gear wheel pairs, and if the engine shaft isconnected with one of the gear wheel pairs by way of a shifting clutch.In order to achieve that with this type of construction, the coupling ofthe engine shaft with the output takes place without shocks, it isadvantageous if the transmission ratio of the gear wheel pair connectedto the input of the converter corresponds inversely to the transmissionratio of the gear wheel pair adapted to be coupled or clutched to theengine shaft. In order to increase the efficiency, it is appropriate ifin the direct speed the engine shaft is adapted to be coupled with theoutput shaft and the converter is adapted to be uncoupled. Efficiencylosses in the converter are avoided thereby in the direct speed.

According to a further feature of the present invention a hydraulicsystem may be provided for the control of the hydrostatic converter andfor the shifting of the shifting clutches, whose control slide valve andshifting valves are actuatable by means of a common shiftinginstallation. It is thereby advantageous if the shifting installationincludes a control cam for the control slide valve of the hydrostaticconverter and shifting cams for the shifting valves which are offsetrelative thereto at distances coordinated to the control positions ofthe converter. An accurate coordination of the individual shiftingoperations can be achieved thereby in a simple manner.

These and other objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in conjunction with the accompanying drawing, which shows, forpurposes of illustration only, one embodiment in accordance with thepresent invention, and wherein:

The single FIGURE is a schematic cross-sectional view through atransmission of the present invention and a schematic diagram of thehydraulic system enabling the shifting operations according to thepresent invention.

Referring now to the single FIGURE of the drawing, an engine shaft 1extends from an engine (not shown) to the transmission, while the gear 2of the pair of gear wheels generally designated by reference numeral 3is arranged on the shaft 1 for rotation in unison therewith. Ahydrostatic pump 4 of a hydrostatic converter generally designated byreference numeral 5 and of conventional construction is driven from theengine shaft 1 by means of the gear wheel pair 3. The hydrostaticconverter 5 further includes a hydrostatic motor 6 of conventionalconstruction whose output shaft 7 is connected with two-geartransmission ratios generally designated by reference numerals 8 and 9and each consisting of a pair of gear wheels, which are operativelyconnected with the output shaft 10 of the transmission connected itselfwith the driven axle (not shown). A hydraulically engageable shiftingclutch 13 is operatively arranged between the gear wheel 11 of the gearpair 8, mounted on the output shaft 7 of the hydrostatic motor 6, andthe gear wheel 12 of the gear pair 9, arranged coaxially thereto. Asimilar shifting clutch 14 is provided between the two other coaxiallydisposed gear wheels 15 and 16 of the two-gear pairs 8 and 9.

The gear wheel 15 of the first gear pair 8, which is disposed coaxiallyto the transmission output shaft 10, is additionally adapted to beconnected with the gear wheel 2 by way of a hydraulically engageableshifting clutch 17. A

The hydrostatic pump 4 and the hydrostatic motor 6 of the hydrostaticconverter 5, which are hydraulically connected with each other in aconventional manner, are provided with adjusting discs or swash plates18 and 19 guided in circular tracks whereby the swash plates 18 and 19,for purposes of achieving a control, are adjustable and delimit thestroke of the pistons 20 and 21 of the pump 4 and of the motor 6,respectively. The adjustment of the discs or plates 18 and 19 takesplace by means of a hydraulically actuatable piston 22 and acorresponding constructed adjusting linkage generally designated byreference numeral 23 and of any conventional construction.

Pressure oil is supplied to the hydraulic system from a gear pump 24arranged on the engine shaft 1, which pressure oil may possibly be heldat a constant level by means of a conventional reservoir or storagedevice generally designated by reference numeral 25. The hydraulicsystem includes a control slide valve member 26 of conventionalconstruction and illustrated only schematically, by means of which thespring-loaded piston 22 of the adjusting installation of the hydrostaticconverter is adapted to be loaded or acted upon with the pressure of thehydraulic medium. The adjustment of the control slide valve member 26takes place by way ofa control cam 27 ofa shifting installation. Addi'tional shifting valves 28, 29 and 30, shown only schematically, areprovided in the hydraulic system, of which the shifting valve 28 isconstructed in such a manner that it is able to short-circuit by meansof one valve section the circulatory system 31 of the hydrostaticconverter 5 within the area of the pump 4 thereby effectively uncouplingthe converter 5 internally. This shifting valve 28 additionally servesby means of another valve section for the purpose of engaging orrelieving (disengaging) of the shifting clutch 17 arranged betweenengine shaft 1 and the gear pair 8. 1n the illustrated position thisshifting valve 28 relieves the shifting clutch l7, i.e., causes the sameto become disengaged, since the clutch 17 is able to discharge thehydraulic actuating medium into the tank 32. The actuation of theshifting valve 28 takes place by way of several shifting earns 33 of theshifting installation.

Each of the shifting clutches l3 and 14 arranged between respectivegears ll, 12 and l5, 16 of the gear pairs 8 and 9, includes its ownshifting valve 29 and 30, respectively, which in'one position thereofconducts pressure oil to the shifting clutches 13 and 14 and in theother position thereof connect the lines leading to the shiftingclutches 13 and 14 with the collecting tank 32 so that the shiftingclutches l3 and 14 can discharge, i.e., can empty the cylinder spacesthereof to become disengaged. The actuation of the two shifting valves29 and 30 also take place by way of shifting cams 34 and 35 of thecommon shifting installation. The shifting clutches 13, 14 and 17 are ofconventional construction andinclude conventional actuating pistons,disengaging springs, etc., while shifting valves 28, 29 and 30 are alsoof conventional construction.

The shifting installation can be displaced, for example, manually bymeans of a shifting knob 36 or the like from the zero position 36'indicated in dot and dash lines from the right toward the left, asviewed in the drawing for purposes of the engagement of the individualshifting ranges. ln such zero position the shifting valve 28 is actuatedby the peak of the first shifting cam 33 to uncouple the converter 5internally by the shortcircuit of the circulation 31 and to adjustingmechanism 22, 23 to maximum torque conversion. In the illustratedshifting position of the shifting installation the shifting valve 30 ofthe upper shifting clutch 13, as viewed in the drawing, is so adjustedthat the shifting clutch 13 is connected with the pressure feed and is,therefore, engaged. The other shifting valves 28 and 29 are so adjustedthat the shifting clutches l4 and 17 are opened or disengaged and thenormal circulation of the hydrostatic converter 5 from its pump 4 to itsmotor 6 exists. As a result thereof, converter 5 is adjusted by valve 26and adjusting mechanism 22, 23 to maximum conversion producing togetherwith the speed reduction of gear pair 9 the maximum overall speedreduction. By a displacement of the shifting installation toward theleft, only the control slide valve member 26 is gradually adjusted bymeans of the control cam 27 which then gradually effects by way of thehydraulic piston 22 the infinitely variable control of the hydrostaticconverter 5. This is readily achieved by a suitable conventionalconstruction of valve 26 to produce the desired gradually varyingthrottling effect by interaction with control cam 27. The control cam 27is so dimensioned that at its end, i.e., with maximum depressing of theslide member 26 at the peak of control cam 27, the speed reduction ratioof 1:] of the hydrostatic converter 5 is attained. Within this range thegear pair 9 constructed as largest speed reduction, for example, with aratio of l :3.5 is operable which together with the converting range,for example, of 1:3.5, of the hydrostatic converter 5 enables thelargest overall speed reduction.

When the complete converting range of the hydrostatic converter 5 istraversed in connection with gear pair 9, a shifting has to take placein which the other gear pair 8 will be rendered operable after theconverter is returned to its initial position, i.e., into its positionof largest torque conversion or speed reduction. This is realized byactuation of the control slide valve member 26 and of the shiftingvalves 28, 29 and 30, by means of the control cam 27 and by means of theshifting cams 33, 34 and 35 arranged at corresponding distances on theshifting installation. As soon as the hydrostatic converter 5 hasreached its transmission ratio of l:l, the shifting clutch 17 betweenthe engine shaft 1 and the gear wheel pair 8 is engaged by displacementof the shifting valve 28 by means of the control cam 33, while at thesame time the circulation 31 of the hydrostatic converter 5 isshort-circuited within the area of the pump 4, resulting in an internaluncoupling of converter 5. Since the hydrostatic converter 5 is thenunable to transmit any torque, the torque of the engine shaft 1 istransmitted in this shifting position to the output shaft 10 exclusivelyby the shifting clutch 17 by way of the gear pair 8, by way of theshifting clutch l3 and byway of the next gear pair 9. ln order to enablein that connection a shock-free engagement of the shifting clutch 17, itmust be assured by an appropriate selection of the speed reduction ofthe gear pair 8 that the rotational speed of the engine shaft 1 existsin the shifting clutch 17 on both sides thereof. Simultaneouslytherewith, the control slide valve member 26 is adjusted by acorresponding configuration and construction of the control cam 27 insuch a manner that the hydrostatic converter 5 assumes the positionwhich corresponds to its maximum speed reduction. If the shiftinginstallation is further displaced toward the left, then the shiftingclutch 17 is opened again and the short-circuit of the circulation 31 ofthe hydrostatic converter 5 is discontinued. At the same time, theshifting valve 29 is actuated by the shifting cam 34 in such amannerthat the shifting clutch 14 is engaged. Simultaneously therewith,the shifting valve 30 is opened by means of a corresponding shifting cam35 of the shifting installation so that the other shifting clutch 13isdisengaged. The shifting to the next shifting range therefore takesplace without interruption of the tractive force between the engine andthe driven wheels.

In the now assumed shifting position, the speed reduction ratio of thehydrostatic converter is controlled by the control cam 27 of theshifting installation. Since the speed reduction ratios of the gear pair3 connected in the input of the hydrostatic converter 5 and of the gearpair 8 in the output thereof are inversely equal for reasons of therotational speed equalization to the engine shaft 1 during shifting, theexisting speed reduction ratio of the hydrostatic converter 5 servesdirectly and exclusively as controlling transmission speed reduction.

After a further displacement of the shifting installation toward theleft, the speed reduction ratio of the hydrostatic converter 5 becomes1:] so that the direct speed is reached. In this position, the shiftingvalve 28 is actuated by a shifting cam 33 of the shifting installationand the clutch l7 adjoining the engine shaft 1 is engaged.Simultaneously therewith the hydrostatic converter 5 is disengaged oruncoupled in the manner described above. A direct transmission of thetorque from the engine shaft 1 to the output shaft 10 then takes placeby way of the shifting clutches l7 and 14.

While 1 have shown and described only one embodiment of the presentinvention, it is understood that the latter is not limited thereto, butis susceptible of numerous changes and modifications as known to thoseskilled in the art. For example, in lieu of the illustrated hydrostaticconverter 5, also all infinitely variable transmission can be used whichpermit an internal uncoupling or disengagement, such as, for instance,friction wheel transmissions. It is only necessary to ensure that aby-passing of the infinitely variable transmission is possible while atthe same time the infinitely variable transmission can be so shiftedthat it does not transmit any torque during such shifting operation.

Additionally, a reverse speed may be readily obtained by moving theshifting knob from its zero or idling position 36 toward the right asviewed in the drawing to the new position indicated in dash and dotlines, whereby the slewing direction of either pump 4 or motor 5 isreversed by conventional means. 5

Since all clutches l3, l4 and 17 are friction clutches permittingslippages, the simultaneous engagement and disengagement of some ofthese clutches or of clutch l7 and of hydraulic converter 5 takes placewith a certain overlap. Consequently, any other slip clutches of knownconstruction may also be used in place of clutches l3, l4 and 17.

Hence, I do not wish to be limited to the details shown and describedherein, but intend to cover all such changes and modifications as areencompassed by the scope of the appended claims.

I claim:

l. A steplesslyadjustable transmission comprising: an input shaft, anoutput shaft, gear means operatively associated with said input shaftand said output shaft for providing at least two mechanical transmissionratios,

ciated with said gear means for selectively providing one of said atleast two mechanical transmission ratios, a second selectivelyengageable means operatively associated with said gear means forselectively providing a second of said at least two transmission ratios,infinitely variable transmission means having an input and an output,said infinitely variable transmission means input being operativelyconnected with said input shaft and said infinitely variabletransmission means output being operatively connected with at least oneof said gear means, said gear means providing at least two power pathsbetween said infinitely variable transmission means and said outputshaft, disabling means operatively connected to said infinitely variabletransmission means for selectively disabling the transmission of torquetherethrough, a third selectively engageable means effectively connectedbetween said input shaft and one of said at least two power paths forenabling said infinitely variable transmission means to be shifted froma first end position to a second end position, said first and secondpositions defining the maximum range of said infinitely variabletransmission means, and a multi-position control means operativelyassociated with said disabling means and said first, second and thirdselectively engageable means for controlling same, said control means ina first position enabling said first selectively engageable means toengage said gear means providing one of said at least two mechanicalratios throughout said maximum range of said infinitely variabletransmission means from said first end position to said second endposition, said control means in a second position enabling saidinfinitely variable transmission means to return to said first endposition by simultaneously engaging said third selectively engageablemeans and said disabling means and thereafter disengaging saidfirstselectively engageable means, said third selectively engageable meansand said disabling means and engaging said second selectively engageablemeans whereby said infinitely variable transmission means can again beshifted substantially over said maximum range with said second of saidat least two transmission ratios engaged without interruption of thetractive force in the transmission.

2. A steplessly adjustable transmission according to claim 1, furtherincluding means for selectively shifting said infinitely variabletransmission means over said maximum range to thereby effect any desiredtransmission ratio possible by said infinitely variable transmisa firstselectively engageable means operatively asso sion means with everymechanical transmission ratio provided by said gear means.

3. A transmission according to claim 1, characterized in that saiddisabling means includes means for internally uncoupling said infinitelyvariable transmission means.

4. A transmission according to claim 3, characterized in that saidinfinitely variable transmission means an infinitely variablehydrostatic converter.

5. A transmission according to claim 1 wherein at least some of saidselectively engageable means are shifting clutch means.

6. A transmission according to claim 5, characterized in that saidinfinitely variable transmission means includes a hydrostatic convertermeans with pump and motor means whose circulation is adapted to beshortcircuited by said-disabling means within the area of its pumpmeans.

7. A transmission according to claim 6 wherein said input of saidhydrostatic converter means is operatively connected with said inputshaft by way of a pair of gear means, said output of said hydrostaticconverter means is adapted to be connected with two selectivelyengageable pairs of said gear means providing said at least two powerpaths and wherein said first and second selectively engageable meansinclude shifting clutch means.

8. A transmission according to claim 7, wherein the transmission ratioof said pair of gear means connected with said input shaft is inverselyequal to the transmission ratio of one of said two selectivelyengageable pairs of gear means.

9. A transmission according to claim 8, wherein said third selectivelyengageable means includes a shifting clutch means and said disablingmeans includes a means for uncoupling said converter means.

10. A transmission according to claim 9, wherein a hydraulic system isprovided in said control means for the control of said hydrostaticconverter means and for the shifting of each of said shifting clutchmeans, said control means includes a control slide valve means, shiftingvalve means, and a common shifting installation.

11. A transmission according to claim 10 wherein said common shiftinginstallation includes a control cam means for said control slide valvemeans and shifting cam means for the shifting valve means which arespaced relative thereto at distances coordinated to the respectivecontrol positions of the converter means.

12 A transmission according to claim 11, characterized in that saiddisabling means includes means for internally uncoupling saidhydrostatic converter means.

13, A transmission according to claim 5, wherein said input of saidinfinitely variable transmission means is operatively connected withsaid input shaft by way of a pair of gear means, said output of saidinfinitely variable transmission means is adapted to be connected withtwo selectively engageable pairs of said gear means providing said atleast two power paths, and wherein said first and second selectivelyengageable means include shifting clutch means.

14. A transmission according to claim 13, wherein the transmission ratioof said pair of gear means connected with said input shaft is inverselyequal to the transmission ratio of one of said two selectivelyengageable pairs of gear means.

15. A transmission according to claim 5, wherein said third selectivelyengageable means includes a shifting clutch means and said disablingmeans includes a means for uncoupling said converter means.

16. A transmission according to claim 5, wherein a hydraulic system isprovided in the control means for the control of said converter meansand for the shifting of each of said shifting clutch means, said controlmeans includes a control slide valve means, shifting valve means, and acommon shifting installation.

17. A transmission according to claim 16, wherein said common shiftinginstallation includes a control cam means for said control slide valvemeans and shifting cam means for the shifting valve means which arespaced relative thereto at distances coordinated to the respectivecontrol positions of the converter means.

18. A transmission according to claim 17, characterized in that saidinfinitely variable transmission means includes a hydrostatic convertermeans with pump and motor means whose circulation is adapted to beshortcircuited by said disabling means within the area of its pumpmeans.

1. A steplessly adjustable transmission comprising: an input shaft, anoutput shaft, gear means operatively associated with said input shaftand said output shaft for providing at least two mechanical transmissionratios, a first selectively engageable means operatively associated withsaid gear means for selectively providing one of said at least twomechanical transmission ratios, a second selectively engageable meansoperatively associated with said gear means for selectively providing asecond of said at least two transmission ratios, infinitely variabletransmission means having an input and an output, said infinitelyvariable transmission means input being operatively connected with saidinput shaft and said infinitely variable transmission means output beingoperatively connected with at least one of said gear means, said gearmeans providing at least two power paths between said infinitelyvariable transmission means and said output shaft, disabling meansoperatively connected to said infinitely variable transmission means forselectively disabling the transmission of torque therethrough, a thirdselectively engageable means effectively connected between said inputshaft and one of said at least two power paths for enabling saidinfinitely variable transmission means to be shifted from a first endposition to a second end position, said first and second positionsdefining the maximum range of said infinitely variable transmissionmeans, and a multi-position control means operatively associated withsaid disabling means and Said first, second and third selectivelyengageable means for controlling same, said control means in a firstposition enabling said first selectively engageable means to engage saidgear means providing one of said at least two mechanical ratiosthroughout said maximum range of said infinitely variable transmissionmeans from said first end position to said second end position, saidcontrol means in a second position enabling said infinitely variabletransmission means to return to said first end position bysimultaneously engaging said third selectively engageable means and saiddisabling means and thereafter disengaging said first selectivelyengageable means, said third selectively engageable means and saiddisabling means and engaging said second selectively engageable meanswhereby said infinitely variable transmission means can again be shiftedsubstantially over said maximum range with said second of said at leasttwo transmission ratios engaged without interruption of the tractiveforce in the transmission.
 2. A steplessly adjustable transmissionaccording to claim 1, further including means for selectively shiftingsaid infinitely variable transmission means over said maximum range tothereby effect any desired transmission ratio possible by saidinfinitely variable transmission means with every mechanicaltransmission ratio provided by said gear means.
 3. A transmissionaccording to claim 1, characterized in that said disabling meansincludes means for internally uncoupling said infinitely variabletransmission means.
 4. A transmission according to claim 3,characterized in that said infinitely variable transmission means aninfinitely variable hydrostatic converter.
 5. A transmission accordingto claim 1, wherein at least some of said selectively engageable meansare shifting clutch means.
 6. A transmission according to claim 5,characterized in that said infinitely variable transmission meansincludes a hydrostatic converter means with pump and motor means whosecirculation is adapted to be short-circuited by said disabling meanswithin the area of its pump means.
 7. A transmission according to claim6 wherein said input of said hydrostatic converter means is operativelyconnected with said input shaft by way of a pair of gear means, saidoutput of said hydrostatic converter means is adapted to be connectedwith two selectively engageable pairs of said gear means providing saidat least two power paths and wherein said first and second selectivelyengageable means include shifting clutch means.
 8. A transmissionaccording to claim 7, wherein the transmission ratio of said pair ofgear means connected with said input shaft is inversely equal to thetransmission ratio of one of said two selectively engageable pairs ofgear means.
 9. A transmission according to claim 8, wherein said thirdselectively engageable means includes a shifting clutch means and saiddisabling means includes a means for uncoupling said converter means.10. A transmission according to claim 9, wherein a hydraulic system isprovided in said control means for the control of said hydrostaticconverter means and for the shifting of each of said shifting clutchmeans, said control means includes a control slide valve means, shiftingvalve means, and a common shifting installation.
 11. A transmissionaccording to claim 10 wherein said common shifting installation includesa control cam means for said control slide valve means and shifting cammeans for the shifting valve means which are spaced relative thereto atdistances coordinated to the respective control positions of theconverter means.
 12. A transmission according to claim 11, characterizedin that said disabling means includes means for internally uncouplingsaid hydrostatic converter means.
 13. A transmission according to claim5, wherein said input of said infinitely variable transmission means isoperatively connected with said input shaft by way of a pair of gearmeans, said output of Said infinitely variable transmission means isadapted to be connected with two selectively engageable pairs of saidgear means providing said at least two power paths, and wherein saidfirst and second selectively engageable means include shifting clutchmeans.
 14. A transmission according to claim 13, wherein thetransmission ratio of said pair of gear means connected with said inputshaft is inversely equal to the transmission ratio of one of said twoselectively engageable pairs of gear means.
 15. A transmission accordingto claim 5, wherein said third selectively engageable means includes ashifting clutch means and said disabling means includes a means foruncoupling said converter means.
 16. A transmission according to claim5, wherein a hydraulic system is provided in the control means for thecontrol of said converter means and for the shifting of each of saidshifting clutch means, said control means includes a control slide valvemeans, shifting valve means, and a common shifting installation.
 17. Atransmission according to claim 16, wherein said common shiftinginstallation includes a control cam means for said control slide valvemeans and shifting cam means for the shifting valve means which arespaced relative thereto at distances coordinated to the respectivecontrol positions of the converter means.
 18. A transmission accordingto claim 17, characterized in that said infinitely variable transmissionmeans includes a hydrostatic converter means with pump and motor meanswhose circulation is adapted to be short-circuited by said disablingmeans within the area of its pump means.